JPH04123599A - Multi-layer dust cap and its forming method - Google Patents

Abstract

PURPOSE:To realize a dust cap whose surface is smooth and beautiful, with excellent heat resistance and high productivity and secular reliability by applying a vibration absorbing member to the surface of a 1st woven cloth comprising thin threads with a small diameter and overlapping a 2nd woven cloth with higher stiffness than that of the 1st woven cloth onto a rear side of a vibration absorbing coat woven cloth to the rear side on which a thermally molten adhesives is applied and molding them. CONSTITUTION:A emulsion of an acrylic resin 1b as a vibration absorbing member is applied to a 'Tetron(R)' woven cloth 1a whose thread diameter and a stitch hole are small and dried and a thermally molten adhesives 1c is applied to the rear side and dried by hot air to form the vibration absorption member applied woven cloth 1. Then a meta alamide fiber woven cloth 2a is immersed in a methanol solution including a phenol resin 2b and squeezed by a roller and dried by hot air to form a phenol resin contained woven cloth 2. It is overlapped to a face of the thermally molten adhesive coating face 1c of the woven cloth 1 so that the phenol resin contained woven cloth 2 is in contact with a male die 3a of a dome shaped heat metallic die and they are heat and press molded. Thus, the dust cap with excellent heat resistance, excellent productivity and secular reliability whose surface is smooth and beautiful is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dust cap for a cone-type speaker.

[Prior Art] As is well known, the dust cap of a cone-shaped speaker is
It is located near the center of the speaker diaphragm and has the function of blocking foreign matter such as dust.In particular, the dust cap connected to the base of the diaphragm affects the vibration mode of the diaphragm, so it is necessary to The diaphragm is required to have sufficient rigidity and a relatively large vibration absorption force to suppress abnormal resonance of the diaphragm. Further, since the dust cap is located near the voice coil and is affected by the heat generated by the voice coil, the dust cap must have high heat resistance in order to increase the input resistance of the speaker.

Typical structures of conventional dust caps that have smooth surfaces or are made of overlapping different materials are, for example, (1)
Molding a polypropylene film.

(2) A thermoplastic vibration absorbing material such as a thermoplastic urethane elastomer film is molded under heat on a base material made of a woven fabric, (3) A material made of a base material made of a woven fabric and a Kuroishi plastic vibration absorbing material film. A product obtained by heating and press-molding a heat-sealable adhesive film having a lower melting point than the thermoplastic vibration-absorbing material film has been put into practical use.

[Problem to be solved] In the conventional dust cap having such a structure,
Dust caps belonging to (1) above have a smooth and beautiful surface, but are highly heat deformable and have a low penetration length; (2);
Dust caps belonging to category (3) have restrictions in terms of design because the unevenness of the fibers appears on the surface and a smooth surface cannot be obtained. Dust caps belonging to category (3) are difficult to manufacture because they are heavy due to the weight of the adhesive film, and air tends to remain between the layers during molding, and the small amount of air remaining may become engraved over time, causing partial peeling. There was an issue that needed to be solved, which was that it caused swelling and swelling.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional examples, and to provide a dust cap with a smooth and beautiful surface, excellent heat resistance, high productivity, and high reliability over time.

[Means for Solving the Problems] A dust cap and a molding method thereof according to the present invention to achieve the above-mentioned object include coating a vibration absorbing material on the surface of a fine first woven fabric made of small diameter yarn, and coating the back surface with a vibration absorbing material. The multilayer dust cap is characterized in that a second woven fabric having higher rigidity than the first woven fabric is layered and molded on the back side of a vibration-absorbing coated woven fabric coated with a heat-sealing adhesive, and the second woven fabric is The cloth is
A multilayer dust cap characterized by being made of fibers that are thicker and more rigid than the first woven fabric, the second woven fabric comprising:
A multilayer dust cap is characterized in that it is a woven fabric impregnated or coated with a stiffening material or a shape imparting material, and the method for forming the multilayer dust cap includes: The second woven fabric is overlapped and the outer periphery is clamped, and the second woven fabric is heated and press-molded so that the convex mold of the heating mold is in contact with the second woven fabric. This method of molding a multilayer dust cap is characterized in that the heat-sealing adhesive is softened and melted, and at the same time, the heat-sealing adhesive is press-fitted into the weave holes of the second woven fabric.

The reason why fibers with a large diameter are used for the second woven fabric is to increase the rigidity and to ensure a sufficient volume of the weave holes to be filled with the softened and melted heat-sealable adhesive.

[Function] Also, in a dust cap configured like this, since the weave volume of the first woven fabric is small, the surface can be smoothed by filling the weave holes with a small amount of vibration-absorbing material, and heat-pressure molding is possible. At times, the heat-sealing adhesive on the back side of the vibration-absorbing coated fabric melts, and the heat-sealing adhesive enters the holes in the second woven fabric. Further, since the second woven fabric is made of highly rigid and large diameter fibers and is impregnated or coated with a stiffening agent or a shape imparting material, the rigidity can be adjusted.

[Example] An example of the present invention will be described in detail with reference to FIGS. 1 and 2. FIG. 1 shows an internal configuration diagram of the dust cap of the embodiment, and FIG. 2 shows an explanatory diagram of the dust cap molding method of the embodiment.

As the first woven fabric, a Tetron woven fabric 1a with a warp of 50 denier, a weft of 75 denier, a thread count of 110 warps/B', a weft of 81/B', and a yarn diameter of 50 g/rl and a small weave hole; Acrylic resin 1 as a vibration absorbing material! Coat the emulsion and dry with hot air at 130°C for 10 minutes. A heat-sealable adhesive 1c made of a copolymer emulsion of ethylene vinyl acetate and acrylic was applied to the back side of the fabric and dried with hot air to produce a vibration-absorbing coated fabric 1 with a weight of 78 g/Ti.

Next, a 2M meta-type aramid fiber woven fabric with 60 x 60 warp/warf threads/@' and 96 g/rl was immersed in a methanol solution containing 30% phenolic resin 2b, and squeezed with a rotating roller and dried with hot air to obtain 116 g/rl. A phenol resin-impregnated woven fabric 2 of rIi was produced. This was superimposed on the heat-sealable adhesive IT side of the vibration-absorbing coated woven fabric L, and the two sides of the phenol resin-impregnated woven fabric were in contact with the convex mold 31 of the dome-shaped heating mold. Heat and pressure mold at 3 kg/ad for about 30 seconds. As a result, the white clay mold descends and comes into contact with the two sides of the phenol resin-impregnated woven fabric, and heat transfers from the white clay mold 3a to the two layers of phenol resin-impregnated woven fabric and then to the 10 layers of heat-sealing adhesive. The heat-sealing adhesive 1c becomes soft from the side of the phenol resin-impregnated woven fabric 2, and instead of entering the slight gaps in the Tetron woven fabric 18 of the vibration-absorbing coat woven fabric 1, it penetrates into the weave holes of the phenolic resin-impregnated woven fabric 2. do. When the heat-sealing adhesive 1c on the side of the vibration-absorbing coated fabric 1 becomes sufficiently soft, the vibration-absorbing coated fabric 1 and the phenol resin-impregnated fabric 2 are in close contact with each other, and the clay mold 31 reaches its bottom dead center. Therefore, the movement of the heat-sealable adhesive 1c due to the pressure is completed, and the inner surface of the vibration-absorbing coated fabric 1 remains almost unchanged, and most of the heat-sealable adhesive 1c is transferred to the fabric of the phenolic resin-impregnated fabric 2. At the same time as the air enters the eye holes, the air on the overlapping surface of the vibration-absorbing coated woven fabric 1 and the phenolic resin-impregnated woven fabric 2 escapes to the outside through the gaps between the unevenness of the white clay mold 3a and the phenolic resin-impregnated woven fabric 2.
Glues without any air remaining. Next, white clay type 3a and student type 3h
During the approximately 27 seconds during which the adhesive is tightened, the heat-sealable adhesive 1c is fused to the phenolic resin-impregnated woven fabric 2, and the phenolic resin 2b of the phenolic resin-impregnated woven fabric 2 is cured, and the external force at the time of mold release is The acrylic resin 1b also adheres more strongly to the inside, and crosslinking progresses, resulting in a dust cap with a smooth and beautiful surface.

Table 1 shows the physical properties of the dust cap obtained in the examples of the present invention and the results of leaving it in a constant temperature bath at 130 degrees Celsius for 12 hours as a heat resistance test.
FIG. 3 shows the frequency characteristics of the speaker used in the cone-shaped diaphragm of AN. For comparison, as a first conventional example, a dust cap made of carbon powder-containing polypropylene having the same shape and weight, and as a second example, a phenol resin-impregnated woven fabric and a polypropylene elastomer with a thickness of 50++ m. Physical properties of a dust cap made by heat-sealing a phenolic resin-impregnated woven fabric and a polypropylene elastomer at the same time as molding at an upper mold temperature of 230°C and a lower mold temperature of approximately 130°C, sandwiching a 5011rn thick heat-sealable adhesive film. The results of the heat resistance test and frequency characteristics are shown in Table 1 and Figure 3, respectively.

In Table 1 and above, the multilayer dust cap and its molding method according to the present invention have been described in detail based on examples that are considered to be representative.
Embodiments of the present invention also apply to woven fabrics, resin materials, etc.
The embodiments are not limited to the above embodiments, and may be implemented with appropriate modifications as long as they have the constituent features set forth in the claims, exhibit the functions defined in the present invention, and have the effects described below. It's Chino.

[Effects] As is clear from Table 1, the dust cap according to the present invention is lightweight, does not have a decrease in Young's modulus, and has a large thickness, so that Et
The rigidity expressed by 3 is large. In addition, it has excellent heat resistance, no deformation due to heat generation of the voice coil, and no air remaining during molding, so it has excellent productivity and reliability over time. , it is possible to provide appropriate rigidity, and the internal loss is large, so
There are few irregularities in the high frequency range of the frequency response, and the surface is smooth and beautiful, which greatly improves the design.

[Brief explanation of the drawing]

Fig. 1 is an internal configuration diagram of the dust cap of the embodiment, Fig. 2 is an explanatory diagram of the dust cap molding method of the embodiment, and Fig. 3 is a frequency characteristic diagram of speakers using the dust caps of the embodiment and the conventional example. . 1 is a vibration-absorbing coated woven fabric, Ill is a Tetron woven fabric, 1b is an acrylic resin, IC is a heat-fusion adhesive, 2 is a phenolic resin-impregnated woven fabric, 2M is a meta-aramid fiber woven fabric, 2b is a phenolic resin, 3a is the 5 superior type, and 3b is the inferior type.

Claims (4)

[Claims] (1) The surface of a fine first woven fabric made of small diameter yarn is coated with a vibration absorbing material, and the back side of the vibration absorbing coated woven fabric is coated with a heat-adhesive adhesive. A multilayer dust cap characterized by being formed by overlapping second woven fabric. (2) The multilayer dust cap according to claim 1, wherein the second woven fabric is made of fibers that are thicker and more rigid than the first woven fabric. (3) The multilayer dust cap according to claim 2 or 1, wherein the second woven fabric is a woven fabric impregnated with or coated with a stiffening material or a shape-imparting material. (4) The method for molding the multilayer dust cap includes stacking the heat-sealable adhesive surface of the first woven fabric and the second woven fabric and clamping the outer periphery, and then applying a convex mold of a heating mold to the second woven fabric surface. so that the molds touch,
By heating and press-molding, the heat from the second fabric is used to form the first fabric.
The heat-sealing adhesive on the back side of the woven fabric is softened and melted, and at the same time the second
A method for molding a multilayer dust cap, characterized in that the heat-sealing adhesive is press-fitted into holes in the weave of a woven fabric.